This PR adds a new `cargo xtask licenses` command for finding crates
with missing license files.
A number of crates were uncovered that were missing a license file, and
have had the appropriate license file added.
Release Notes:
- N/A
I saved the `file_types.json` file and got a diff because it had some
trailing whitespace. I ran
[`lineman`](https://github.com/JosephTLyons/lineman) on the codebase.
I've done this before, but this time, I've added in the following
settings to our `.zed` local settings, to make sure every future save
respects our desire to have consistent whitespace formatting.
```json
"remove_trailing_whitespace_on_save": true,
"ensure_final_newline_on_save": true
```
Release Notes:
- N/A
